I'm been working on chapter 13, book 1, of Calvin's institutes. Here John is working on the theology of the Trinity, a series of proofs that Jesus Christ and the Holy Spirit are God and he addresses a bunch of various heresy doctrines. If there is any doubt in your mind that the mid-1500's are so similar to our current culture just consider that Calvin refers to the developers of heresy doctrine as "slippery snakes". I don't believe the world has changed too much except that John Calvin was not on Facebook or Twitter. A little more interesting is Calvin's logical argument for the Trinity which centers around the early Church's translation of a Greek word; one translation to "substance" leads down one theological path while using the translation "essence" leads some where else. In the end, Calvin considers faith the central core for our understanding of the Trinity and I agree.